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Skinmap improvement.

Browse Source 
Use a flag to switch between original skinmap model and an
experimental model(use original skinmap by default).

BUG=

Review URL: https://codereview.webrtc.org/1776993004

Cr-Commit-Position: refs/heads/master@{#11956}
This commit is contained in:
jackychen
2016-03-11 11:57:03 -08:00
committed by Commit bot
parent 86aabb288d
commit 3ad4bd31cc
2 changed files with 49 additions and 15 deletions
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62
webrtc/modules/video_processing/util/skin_detection.cc
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@ -16,30 +16,66 @@
namespace webrtc {
// Fixed-point skin color model parameters.
static const int skin_mean[2] = {7463, 9614}; // q6
static const int skin_mean[5][2] = {
{7463, 9614}, {6400, 10240}, {7040, 10240}, {8320, 9280}, {6800, 9614}};
static const int skin_inv_cov[4] = {4107, 1663, 1663, 2157}; // q16
static const int skin_threshold = 1570636; // q18
static const int skin_threshold[6] = {1570636, 1400000, 800000, 800000, 800000,
800000}; // q18
// Thresholds on luminance.
static const int y_low = 20;
static const int y_low = 40;
static const int y_high = 220;
// Evaluates the Mahalanobis distance measure for the input CbCr values.
static int EvaluateSkinColorDifference(int cb, int cr) {
static int EvaluateSkinColorDifference(int cb, int cr, int idx) {
const int cb_q6 = cb << 6;
const int cr_q6 = cr << 6;
const int cb_diff_q12 = (cb_q6 - skin_mean[0]) * (cb_q6 - skin_mean[0]);
const int cbcr_diff_q12 = (cb_q6 - skin_mean[0]) * (cr_q6 - skin_mean[1]);
const int cr_diff_q12 = (cr_q6 - skin_mean[1]) * (cr_q6 - skin_mean[1]);
const int cb_diff_q12 =
(cb_q6 - skin_mean[idx][0]) * (cb_q6 - skin_mean[idx][0]);
const int cbcr_diff_q12 =
(cb_q6 - skin_mean[idx][0]) * (cr_q6 - skin_mean[idx][1]);
const int cr_diff_q12 =
(cr_q6 - skin_mean[idx][1]) * (cr_q6 - skin_mean[idx][1]);
const int cb_diff_q2 = (cb_diff_q12 + (1 << 9)) >> 10;
const int cbcr_diff_q2 = (cbcr_diff_q12 + (1 << 9)) >> 10;
const int cr_diff_q2 = (cr_diff_q12 + (1 << 9)) >> 10;
const int skin_diff =
skin_inv_cov[0] * cb_diff_q2 + skin_inv_cov[1] * cbcr_diff_q2 +
skin_inv_cov[2] * cbcr_diff_q2 + skin_inv_cov[3] * cr_diff_q2;
const int skin_diff = skin_inv_cov[0] * cb_diff_q2 +
skin_inv_cov[1] * cbcr_diff_q2 +
skin_inv_cov[2] * cbcr_diff_q2 +
skin_inv_cov[3] * cr_diff_q2;
return skin_diff;
}
static int SkinPixel(const uint8_t y, const uint8_t cb, const uint8_t cr) {
if (y < y_low || y > y_high) {
return 0;
} else {
if (MODEL_MODE == 0) {
return (EvaluateSkinColorDifference(cb, cr, 0) < skin_threshold[0]);
} else {
// Exit on grey.
if (cb == 128 && cr == 128)
return 0;
// Exit on very strong cb.
if (cb > 150 && cr < 110)
return 0;
// Exit on (another) low luminance threshold if either color is high.
if (y < 50 && (cb > 140 || cr > 140))
return 0;
for (int i = 0; i < 5; i++) {
int diff = EvaluateSkinColorDifference(cb, cr, i);
if (diff < skin_threshold[i + 1]) {
return 1;
} else if (diff > (skin_threshold[i + 1] << 3)) {
// Exit if difference is much large than the threshold.
return 0;
}
}
return 0;
}
}
}
bool MbHasSkinColor(const uint8_t* y_src,
const uint8_t* u_src,
const uint8_t* v_src,
@ -55,11 +91,7 @@ bool MbHasSkinColor(const uint8_t* y_src,
uint8_t y_avg = (*y + *(y + 1) + *(y + stride_y) + *(y + stride_y + 1)) >> 2;
uint8_t u_avg = (*u + *(u + 1) + *(u + stride_u) + *(u + stride_u + 1)) >> 2;
uint8_t v_avg = (*v + *(v + 1) + *(v + stride_v) + *(v + stride_v + 1)) >> 2;
// Ignore MB with too high or low brightness.
if (y_avg < y_low || y_avg > y_high)
return false;
else
return (EvaluateSkinColorDifference(u_avg, v_avg) < skin_threshold);
return SkinPixel(y_avg, u_avg, v_avg) == 1;
}
} // namespace webrtc

2
webrtc/modules/video_processing/util/skin_detection.h
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@ -13,6 +13,8 @@
namespace webrtc {
#define MODEL_MODE 0
typedef unsigned char uint8_t;
bool MbHasSkinColor(const uint8_t* y_src,
const uint8_t* u_src,